Silverlight Gridcolumn Collapse Visibility in code

I'm having a small problem.

I have this grid with a column:

<data:DataGrid ColumnHeaderStyle="{StaticResource headerStyle}" Foreground="#234BC3" AutoGenerateColumns="False" Name="protocollenBAMDataGrid" LoadingRow="myDataGrid_LoadingRow" SelectionChanged="DataGrid_SelectionChanged">
                    <data:DataGrid.Columns>
                        <data:DataGridTemplateColumn Header="Resend" x:Name="ResendColumn">
                            <data:DataGridTemplateColumn.CellTemplate>
                                <DataTemplate>
                                    <Button Content="Resend" Tag="{Binding MsgID}" Foreground="#234BC3" Click="dataGridHL7_Click"></Button>
                                </DataTemplate>
                            </data:DataGridTemplateColumn.CellTemplate>
                        </data:DataGridTemplateColumn> ...

If i set the visibility of the "ResendColumn" to collapsed, it works fine.

However I need to do this in code, so I tried doing this in the loading event:

ResendColumn.Visibility = Visibility.Collapsed;

And i开发者_如何转开发t gives me a nullref exception:

Object reference not set to an instance of an object.

I don't understand why?

I get the same behaviour in SL 4. I guess it is related to the column not being a UIElement and thus instantiated by the DataGrid itself (not by the usual stuff happening in InitializeComponent).

I had to access the columns through the Columns property of the DataGrid. And there, setting the visibility works.